Sheet slitting device



w, as, 1946,

SHEET SLI'ITING DEVI GE Filed April 26, 1945 2 Sheets-Sheet 1 INVENTOR.

Y BY James A 'a/e I ATTORNEY J. A. GALE v 2,409Q203 SHEET SLITTINGDEVICE Filed April 26, 1945 2 Sheets-Sheet 2 4 I INVENTOR. James A. GaleJ. A. GALE 2,409,203

Patented Oct. 15, 1946 UNITED STATES PATENT OFFICE SHEET SLITTINGDEVICEJames A. Gale, New York, N. Y.

. Application April 26, 1945, Serial No. 590,445

3 Claims. (01. 164-73) (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) This invention concerns anapparatus for slitting sheet material and particularly the inventionconcerns an apparatus for slitting sheets of cellulosic material,synthetic resin or plastic material into long narrow strips.

In determining the physical characteristics of thin sheet material suchas cellulosic film, two important tests are for tensile strength andelongation. For the purpose of making such tests it is found convenientto use specimens in the form of relatively long narrow strips and it iscustomary to cut specimens of such shape from larger sheets of materialby slitting the sheets.

In performing tests to determine tensile strength and elongation onsheet material it is necessary that the results of the tests be accurateand give an indication of true value. To achieve this end it iscustomary to run tests on a number of specimens and compute an averageof the results obtained in order that slight deviations from true valuein individual specimens will compensate each other and not show up inthe computed average.

It is further necessary in performing such tests that the resultssecured shall be reproducible, that is, that the results secured fromany sample shall be consistent with the results secured from any othersample and that variations in results from different specimens shall besmall.

Cellulosic materials such as photographic film inherently have hightensile strength and low tearing strength. In performing tension andelongation tests it has been found that rupture of the specimen iscaused by a combination of failure due to tension and failure due totearing. In order that the tearing effect may be kept at a minimum andthat true tensile strength and elongation values may be obtained it isnecessary that the specimens be cut in such a manner that the edges arefree from nicks, cuts or other imperfections since these are incipientpoints of tear. It can therefore be seen that the value of tensilestrength and elongation obtained in such tests is to a large measureafiected by the apparatus used in cutting the test specimens from alarger sheet and the condition of the edges of the test specimen aftercutting. Experience has proven and microscopic examination of the edgesof'specimen's cut by various devices substantiate that the use of anextremely sharp cutting edge such as a razorblade operating in free airgives the cleanest cut and one which is for practical purposes free fromnicks or rough spots.

Previous methods used for the preparation of test; specimens consistedof laying the sheet of material to be slit upon a bedplate of material,such as linoleum, and manually cutting it with a knife blade or razor.Such methods have proven inadequate since the edges of the specimen cutin this manner were nicked and otherwise imperfect so that thetensilestrength and elongation values obtained upon testing suchspecimens were completely unreliable, inaccurate and not reproducible.

This invention provides an apparatus in which a sheet of material, suchas cellulosic film, is slit into relatively long narrow specimens with aplurality of razorblades operating in free air. The apparatus provides aslotted bedplate having clamps to hold the sheet of material in positionover the slots while being cut by series of sharp cutting tools thatextend into the slots and that are supported on a carriage which slidesover the bedplate. vention to slit a sheet of material with precisionand insure that the specimens produced have clean edges, which are forpractical purposes, free from nicks or other imperfections and whichgive true values of tensile strength and elongation when tested. Valuesof tensile strength made on specimens cut on the apparatus forming thesubject matter of this invention are higher than for specimens producedby other apparatus. Elongation at rupture of 25 to 30% have beenobtained on specimens of material produced by the apparatus of thisinvention, which material when tested by specimens produced on otherapparatus had elongation values so low as to be impossible ofmeasurement.

Values of tensile strength and elongation secured from samples producedby the apparatus of this invention are reliable, accurate andreproducible.

An object of this invention is to provide an apparatus for slittingsheets into relatively long narrow strips.

- A further object is to provide an apparatus for slitting sheetmaterial into specimen strips having edges which are clean and unbrokenand which are free from nicks or other imperfections.

A further object is to provide an apparatus for slitting sheet materialinto specimen strips which give a true indication of tensile strengthand elongation when tested and which are free from imperfections causingdistortions of test values.

Further objects and advantages of this invention, as well as itsconstruction, arrangement and operation, will be apparent from thefollowing description and claims in connection with the accompanyingdrawings in which:

It is possible by using the present in- I Figure 1 is a perspective viewof a preferred form of the invention.

Figure 2 is a perspective view similar to Figure 1 but taken from apoint of View 180 removed from the view point of Figure 1.

Figure 3 is a detailed view showing in section the method of mountingone of the clamps of this invention.

Figure 4 is a detailed view showing in section the spring cushion forthe clamp of Figure 3.

Figure 5 is a detailed view showing in section the mounting for thesecond clamp of this invention.

Figure 6 is a fragmentary view in elevation showing the construction formounting the carriage of this invention upon its baseboard,

Figure '7 is a fragmentary view showing the construction for mounting acutting tool in the carriage.

Referring to the drawings in detail and with particular reference toFigures 1 and 2, there is illustrated a, bedplate having a workingsurface |2 which is preferably flat and rectangular in shape and uponwhich is positioned a sheet of material I 9 (shown in phantom lines) tobe slit into strips. Bedplate I I may be made of any suitable materialsuch as Bakelite. A series of parallel slots I3 are disposedlongitudinally in working surface I2 and are spaced apart a widthcorresponding to the width of the specimen strips which it is desired tocut. Slots I3 are of a depth suflicient to accommodate the dependingportion of cutting tools which will be hereinafter described.

Abar clamp I4 is provided at one end of working surface 12 and isdisposed transversely to slots I3. Bar clamp I4 has a lower face |5which is flat in contour and located in opposed relation to workingsurface I2. Fastened to face I5 in any suitable manner is a frictionstrip I5 which may be made of any suitable material such as rubber.Referring to Figure 3 it will be seen that bar clamp I4 is adjustablysecured with respect to bedplate II by means of a pair of screws I! eachof which is threaded into the bedplate and M has an upwardly extendingportion which extends through an opening in bar clamp I4. A handnut I8on each screw I'I secures bar clamp I4 in place and nuts I8 may betightened to actuate bar clamp I4 toward working surface I2 or may beloosened to allow withdrawal of bar clamp I4 away from working surfaceI2. Referring to Figure 4, it will be seen that bar clamp I4 iscushioned upon a pair of springs I9 which constantly urge bar clamp I4away from working surface I2 in order that one edge of a piece ofmaterial II! to be slit may be inserted thereunder. Each spring |9reacts at one end within a recess in bedplate II and at its other endreacts within a recess 2| in face I5 of bar clamp Arranged near theopposite end of working surface I2 is a second bar clamp 22 arrangedtransversely to slots I3. Bar clamp 22 has a lower face 24 which is fiatand located in opposed relation to working surface I2. A friction strip25 of any suitable material such as rubber is secured 'in any suitablemanner to surface 24. Referring to Figure 5, .it will be seen that barclamp 22 is cushioned upon a pair of springs 26 which constantly urgebar clamp 22 away from working surface I2 in order that one edge of apiece of material I0 may be inserted thereunder. Each spring 26 reactsat one end in a recess '21 in bedplate II and reacts at its other end ina threaded into bedplate II and extends upwardly through slot 34 inoffset 32. A pair of hand nuts 35 one on each screw 33 is provided toadjustably secure brackets 3| with respect to bedplate II. Handnuts 35may be tightened to urge brackets 3| and bar clamp 22 toward workingsurface I2 01' may be loosened to allow movement of brackets 3| and barclamp 22 away from workin surface 12.

Provided along the sides of working surface I2 is a pair of guide rails39 which are preferably cylindrical in shape and which are disposedparallel to slots I3, being secured to bedplate II by screws 43. Theheads of screws 40 are countersunk into the top of rails 39 except forthe end screws in each rail 39 adjacent bar clamp 22 which protrudeabove the top of rails 39 to form stops 4| for a sliding carriage 42.

Carriage 42 is mounted for sliding movement on guide rails 39 and has anH-shaped frame consisting of parallel legs 43 and a crossbar 44 which iscountersunk at its ends into the top of legs 43 and secured in place byscrews 45. Each leg 43 at its extremities is provided with a pair ofslide blocks 46 secured to its under surface by screws 41. Slide blocks46 on each leg are provided with aligned bores 48 whereby the slideblocks and carriage 42 may be mounted upon guide rails 39 for slidingmotion. Slide blocks 46 are constructed to have a snug fit with respectto guide rails 39 whereby easy sliding movement of carriage 42 uponguide rails 39 is permitted while lateral movement transversely of slotsI3 is prevented.

With reference to Figure 6, spaced vertical extending lugs 49 arecountersunk into the top surface of crossbar 44 and secured in place bymeans of screws 59. Lugs 49 are provided with aligned bores 5| throughwhich extends a shaft 52. Shaft 52 is threaded throughout its entirelength and is provided with a flat side 53 for a purpose hereinafterdescribed. A pair of locknuts 54 are threaded on shaft 52 against theoutboard surface of each of lugs 49 serving to lock shaft 52 againstlateralmovement relative to carriage '42.

Mounted upon shaft 52 is a series of spaced fingers 55 each having abottom surface 56 (Figure 7) and each being secured against rotation bya set screw 5'! threaded against the fiat side 53 of shaft 52. Apair oflocknuts 58 to hold each finger 55 against lateral movement is threadedon shaft 52 with one locknut 58 on each side of a finger 55. Each finger55 is provided with a portion 59 which serves as a tool holder for acutting tool fill which .may be of any suitable construction and may, ifdesired, be in the form of a razorblade as illustrated in Figure '7. Alocking plate 6| is mounted on each tool holder for multiple strips.

locknuts 58 and set screws 57 and then position- 1 ing fingers 55laterally upon shaft 55 so that each cutting tool 66 is centrallyaligned with a slot l3 and the cutting tools are spaced apart a distancecorresponding to the width of the strips which it is desired to out fromthe sheet of material. Fingers 55 are then looked upon shaft 52 by tightening set screws 51 and locknuts 58.

A sheet of material to be slit is loaded into the machine as follows.Handle 66 is depressed to rotate shaft 52 so that cutting tools til arewithdrawn from slots l 3, and carriage 42 is reciprocated on guide rails39 to the end of working surface 12 adjacent clamp 22 and against stopscrews 1!. Working surface I 2 between clamps I 4 and 22 is thus leftclear. Clamp I4 is loosened by unscrewing handnuts l8, and clamp 22 isloosened by unscrewing handnuts 35. A sheet of material to be slit isthen laid on working surface l2 of bedplate H with the ends thereofunder clamps it and 22. Clamp I4 is then secured by tightening handnutsl8 and clamp 22 is secured by tightening handnuts 35 to clamp the sheetof material in place for slitting.

With handle 84 still depressed, carriage 42 is reciprccated on guiderails 39 to the end of working surface [2 adjacent clamp M and clamp I4will serve as a stop for carriage 62 when the latter comes into abutmenttherewith. Handle 64 is next raised to rotate shaft 52 and depresscutting tools 6% which will puncture the sheet of material and extendinto slots l3. Carriage 42 is then reciprocated on guide rails 39 towardclamp 22 whereby tools 68 slit the sheet of material into Handle 54 isthen depressed to raise cutting tools so and is reciprocated to the endof bedplate H against stop screws 41 adjacent clamp 22. Clamps Id and 22are then loosened as above described and the sheet of material in slitcondition removed from the machine.

The limits of throw for handle 64 are determined by contact of handle 64with carriag legs 43 on the downward stroke, and abutment of fingerfaces 55 (Figure 7) with carriage crossbar M on the upward stroke.

It i to be understood that various modifica- :zs'

tions and changes may be made in this invention without departing fromthe spirit and scope thereof as set forth in the appended claims.

The invention described herein may b manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. A sheet slitting device comprising a bedplate having fiat workingsurface adapted to have a sheet of material to be slit imposed thereon,said working surface defining a plurality of parallel slots, a pair ofspaced clamping bars arranged transversely of said slots, said barshaving friction surfaces opposed to said working surface,

resilient means for urging said bar away from said working surfacewhereby opposite edges of a sheet of material may be inserted betweensaid working surface and said friction surfaces, means for clamping saidbars against said working surface to secure the sheet thereon, guiderails on said bedplate parallel to said slots, a carriage mounted onsaid rails for reciprocation in a line parallel to said slots, a shaftrotatably mounted on said carriage and disposed transversely of saidslots, spaced fingers rigidly secured to said shaft, cutting toolssecured to said fingers, and means for adjusting said fingers on saidshaft whereby said tools may be aligned with said slots, said shaftbeing arranged for rotation into cutting position whereby said tools aredepressed in unison into said slots with the cutting edges thereofdisposed to slit the sheet of material and being further arranged forrotation in unison into inoperative position whereby said tools arewithdrawn from said slots.

2. A sheet slitting device comprising a bedplate having a flat workingsurface adapted to have a sheet of material to be slit imposed thereon,said working surface defining a plurality of parallel slots, means forsecuring a sheet to be slit upon said working surface, guide rails onsaid bedplate parallel to said slots, a carriage mounted on said railsfor reciprocation in a line parallel to said slots, a shaft rotatablymounted on said carriage and disposed transversely of said slots, spacedfingers rigidly secured to said shaft, cutting tools secured to saidfingers, and means for adjusting said fingers on said shaft whereby saidtools may be aligned with said slots, said shaft being arranged forrotation into cutting position whereby said tools are depressed inunison into said slots with the cutting edges thereof disposed to slitthe sheet of material and being further arranged for rotation in unisoninto inoperative position whereby said tools are withdrawn from saidslots.

3. A sheet slitting device comprising a bedplate having a flat workingsurface adapted to have a sheet of material to be slit imposed thereon,said working surface defining a plurality of parallel slots, a pair ofspaced clamping barsarranged transversely of said slots, said barshaving friction surfaces opposed to said working surface, resilientmeans for urging said bars away from said working surface wherebyopposite edges of a sheet of material may be inserted between saidworking surface and said friction surfaces, means for clamping said barsagainst said working surface to secure the sheet thereon, guide rails onsaid bedplate parallel to said slots, a carriage mounted on said railsfor reciprocation in a line parallel to said slots, said carriage havinga portion extending transversely of said slots, spaced fingers supportedon said transverse portion, cutting tools secured to said fingers, andmeans for adjusting said fingers on said transverse portion whereby saidtools may be aligned with said slots, and means for moving said tools inunison into cutting position with the cutting edges thereof disposed toslit in said working surface a sheet of material, said means beingarranged for moving said tools in unison into inoperative position withthe cutting edges thereof withdrawn from the working surface.

JAlVLES A. GALE.

